This invention relates to a squeeze pump in which a resilient tube disposed arcuately in a pump casing is pressed by presser rolls moved along the resilient tube, the presser rolls being freely rotated about their axes, to thereby continuously transfer slurry contained in the tube.
The squeeze pump, known in the art as shown in FIG. 1, comprises a resilient tube 2 bent arcuately and placed along an inner periphery of a pump casing 1, and a plurality of presser rolls 5 carried by a rotary arm 4 parallel to a rotary arbor 3 and integral with the rotary arm 4. Upon rotation of the rotary arm 4 in the direction of the arrow marked in FIG. 1, the respective presser rolls 5 roll on the resilient tube 2, wherein the tube 2 is clamped between the rolls 5 and the inner periphery of the pump casing 1, for transferring slurry in the tube 2.
In particular, when concrete slurry including aggregates 6 therein is transferred by the conventional squeeze pump as shown in FIG. 1, the tube 2 is gradually pressed by the presser roll 5 against the inner periphery of the pump casing 1. Pressing procedure of the tube 2 by means of the roll 5 is shown in FIGS. 15(a)-15(d).
In FIG. 15(a), the roll 5 has begun to press the tube 2, in which the tube 2 is still round. As the rotary arbor 3 rotates, the roll 5 presses the tube 2 against the casing 1 as shown in FIG. 15(b), wherein the slurry and aggregates inside the tube 2 can still move freely. When the rotary arbor 3 further rotates, aggregates 6 are caught inside the tube 2 as shown in FIG. 15(c). Since one side of the tube 2 adjacent to the roll 5 is gradually pressed or moved toward the opposite side of the tube 2 adjacent to the casing 1, aggregates in the slurry located adjacent to the casing are not pushed in any direction. Therefore, although some aggregates may still escape from being caught by inner sides of the tube 2, at least some aggregates are caught as shown in FIG. 15(c). In this situation, when the roll 5 further rotates, aggregates stick in the tube 2 as shown in FIG. 15(d).
Further, when the roll 5 is moved along the inner periphery of the casing 1, some aggregates may be caught inside the tube because an angle a is not wide enough to push aggregates outwardly as shown in FIG. 15(e). Therefore, aggregates will further stick in the tube.
As stated above, if a conventional squeeze pump is used to transfer the concrete slurry with aggregates, aggregates will be caught or nipped inside the tube. Aggregates may even stick into the tube. Consequently, the tube may be easily worn out or torn. The conventional squeeze pump is not suitable to transfer concrete slurry.
Further, in this known type of the squeeze pump, since the resilient tube 2 is pressed by the presser rolls 5 onto the inner peripheral surface of the pump casing 1, such peripheral surface must be accurately arcuate for stably clamping the resilient tube 2 between the presser rolls 5 and the inner peripheral surface of the pump casing 1. Moreover, to prevent the damage of the resilient tube 2, such peripheral surface must be ground to a smooth surface, while the rotary shaft 3 must be centered accurately in the pump casing 1 so that the presser rolls 5 may accurately follow the inner peripheral surface of the pump casing 1.
On the other hand, when the resilient tube 2 is mounted in the casing 1 in an arcuate form along the arcuate surface, the tube 2 may be elliptical in cross-section and moreover the tube 2 is pressed by the rolls 5 in a direction to further flatten the ellipsis. As a result, the tube 2 may be restored simply to an elliptical cross-section after the presser rolls 5 have passed thereon. Thus, the tube 2 may be deformed permanently to an elliptical cross-section with prolonged use resulting in the reduction of the slurry quantity to be transferred. In addition thereto, since the tube 2 is pressed onto the inner peripheral surface of the pump casing 1, the tube 2 tends to be elongated slightly and heated due to strong friction caused by pressure contact between the tube 2 and the peripheral surface, thus causing premature wear of the tube 2.
This invention has been made to overcome these deficiencies and has an object to provide a squeeze pump wherein the slurry is transferred effectively, the resilient tube is improved in durability by preventing wear thereof and manufacture is facilitated.
It is another object of the present invention to provide a squeeze pump wherein a slurry with solid materials can be effectively transferred without wear of the tube.
It is another object of the present invention to provide a squeeze pump wherein the tube has improved restorability after pressing, resulting in improved efficiency of slurry suction by the resilient tube.
It is another object of the present invention to provide a squeeze pump wherein the inner peripheral surface of the pump casing need not have a ground finish and the rotary arbor may be centered roughtly, resulting in the reduced manufacture costs of the overall device.
It is another object of the present invention to provide a squeeze pump wherein a rib is mounted at the center of the inner peripheral surface of the pump casing for setting the radius of bend of the resilient tube, whereby the mounting of the tube within the pump casing is facilitated.
It is another object of the present invention to provide a squeeze pump wherein tube fatigue to be caused at the start and termination of clamping of the resilient tube is reduced.
It is another object of the present invention to provide a squeeze pump wherein the solid materials contained in the slurry do not encroach on the inner surface of the tube during pressing of the tube by the presser rolls to prevent the wear of the tube.
It is yet another object of the present invention to provide a squeeze pump wherein the presser rolls positively press the tube without slipping.